Pump



March 15 1948- R. s'roun-:NBERG r-n' AL 2,437,897`

PUMP

Filed Dec. 29, 1944 0 0 O 0 0 O 0 O 0 OOO O 0 0 0 0 ATTORNEY Patented Mai'.l 16, 1948 UNITED STATI-:s PATENT ori-ics PUMP Glenn R. Stoltenberg, New York, N. Y., and August P. Colaiaco, Wilkinsburg, Pa., assignors, by menne assignments, to the United States of n America as represented by the United States r Atomic Energy Commission Application December 29, 1944, Serial No. 570,418

. 7 Claims. l

Our invention relates to pumps and, particularly, to self-fractionatlng oil-diffusion pumps.

In the operation of fractionating diffusion pumps, it has heretofore been customary to provide separate boiler compartments for each pumping stage of the pump, and to circulate the pumping iiuld from the various compartments of the lpump as the fractions'are distilled off.

According to our invention, a selffractionating pump is provided, utilizing a common boiler for all of the pumping stages. In order to secure the evolution of the various volatiles at different points on the surface of the liquid in the boiler, the boiler is divided into a plurality of cells, and the pumping fluid retarded in the cells until the various volatiles have been evolved. These cells may either be concentric ring-like-cells, or may be a plurality of relatively well-like cells provided by a metallic grid structure. The circulation of the oil or other vapor-evolving liquid is retarded by providing relatively restricted openings so disposed that the liquid entering the boiler is rst admitted to one group of cells, and then passed to a succeeding group of cells.

In order to separate the various volatiles at the pumping nozzles, independent chimneys are provided for each nozzle or jet, the bottom of the chimneys being extended in proximity with they surface of the liquid in the boiler, and preferably provided with baiiies to impede the flow of vapor adjacent to the surface of the liquid in the boiler.

It is an object of our invention to provide a self-fractionating pump. utilizing a. common boiler for all pumping stages.

It is a further object of our invention to provide a boiler structure which reduces the turbulence of the boiler liquid.

It is a further object of our invention to provide a boiler structure which will separate out' any foreign matter found in the vapor-evolving material. l

It'is a further object of our invention to provide a boiler structure in which all portions of the vapor-evolving liquid are substantially uniformly heated,

Other objects and advantages of our invention will be apparent in the following detailed description, taken in conjunction with the accompanying drawing, in which:

Figure l is a sectional elevation of a pump according to our invention;

Fig. 2 is a partial plan view, showing one method of providing the boiler cells;

Figs. 3 and 4 are fragmentary views, showing a further method of providing the boiler cells.

In an exemplary embodiment of our invention, a. multiple-stage pump, herein shown as a two-' stage pump for simplicity of illustration, is provided with a pumping chamber I0 having an opening II- to the space to be evacuated and a discharge opening I2 to any suitable backing pump (not shown). The pumping jets I3 and Il are herein shown as of the down-draft variety; but, obviously, the invention is applicable to any type of diffusion pump.

The boiler or vapor-evolving compartment I5 of the pump is placed adjacent the bottom of the pump chamber and is divided into a plurality of vapor-evolving cells I6. These vapor-evolving cells I6 may be constructed in a variety of ways.

In the embodiment according to Figures 1 and 2, the cells I6 are constructed of substantially cubical formation by means of a metallic grid-y like member Il inserted in the boiler I5. Preferably, the grid-like member Il is of such a height as to be normally immersed in the vaporevolving iluld I8. Suitable Apassages I9 are provided betweenl the various cells I6 to permit an impeded fluid flow/from theouter to the inner cell structures. The cell structures not only retain the Huid I8 until certain volatiles have been evolved, but lthey further aid the action of the u J.pump by providing settling chambers in which .any dirt or foreign matter will be separated outj in the cells I6 adjacent the exterior of the pump.

The cell structure further prevents excessive turbulence of the vapor-evolving fluid I8 by preventing random flow of the liquid and separating the liquid intol relatively small areas. The metallic nature of the cell-forming bodies I'I also distributes the heat substantially uniformly to all portions of the liquid I8 which further reduces turbulence of the liquid. l.

It is desirable to conduct the most volatile materials to the jet having the v,higher pressure, that is, the discharge jet I4; and, accordingly, the

chimney 20 supplying vapor to the high-pressure jet I4 is associated with that portion of the boiler surface from which the most volatile materials are evolved. The jet l,I3 associated with the intake or low-pressure' side of the pump would have the least volatile material supplied thereto; and, therefore, the chimney 2| supplying the lowpressure jet I3 is associated with the area of the boiler I5 from which the least volatile materials are evolved.

In order to prevent intermingling or migration of the vapors evolved under the various chimneys 2li-2|, the .bottoms of the chimneys are extended in proximity to thesurface of the vapor-evolving liquid I8, preferably being separated by a space of the order of 1A; to 1/4 inch. Additional bafiles 22-23 are usually provided to increase the degree of separation or.impede the now of vapor along the surface of the 'liquid I8.

In the operation of the pump according to our invention condensate from the various iets IJ-H will be returned to the outside cells IS, where they will be heated and the higher volatiles will be evolved and pass into the chimney 20 connected with the high-pressure Jet I4. The liquid stripped of its higher volatiles will pass through the openings I9 to-the'adjacent cells, where the -less high volatile materials -will be evolved. The ultimate cells I6 thereby evolve the lower volatile materials which pass through the chimney 2| connected with the low-pressure jet I3, the bailles 22-23 between the chimneys 2li- 2l serving to prevent intermingling of the lower and higher volatile materials.

In the modification according to Figs. 3 and 4, the cells I 6 araprovided by means of concentric ring-like baffles I Il which are preferably so connected that the vapor-evolving liquid traverses the rings quite slowly, and preferably so that the liquid must travel substantially the length of the cell before being admitted to the adjacent cell.

For reasons of simplicity, we have'shown and described preferred embodiments of our invention; however, it will be apparent to those skilled in the art that changes and modifications can be made therein without-departing fromvthe true spirit of our inventioILor the scope of the appended claims.v

.We claim as our invention:

1. A vacuum pump comprising a substantially cylindricalpump chamber, a plurality of axially spaced pumping jets in said chamber, a plurality of coaxial vapor passages for delivering vapor to said jets, a common boiler adapted to contain pumping liquid for producing the pumping vapor, means in closely-spaced relationabove the level of said liquid for associating the vapor passages with predetermined portions of the surface of the liquid in the boiler said means including a depending baille for impeding migration ofV pumping vapor, and means in said boiler for controlling the quality of the vapor evolved in the a several portions of the boiler.

2. A vacuum pump comprising a substantially cylindrical pump chamber, a plurality of axially spaced pumping jets in said chamber, a plurality of coaxial vapor passages for delivering vapor to said jets, a common boiler adapted to contain pumping liquid for producing the pumping vapor, means in closely-spaced relation above the level of said liquid for associating the vapor passages with predetermined portions of the surface of the liquid in the boiler and supporting a plurality of depending bailles .adapted to impede migration of pumping vapors along the surface of said liquid, means for returning condensed liquid t the outer portion of the boiler and means in said boiler for control-ling the flow of liquid from the outer portion to the inner portion of the boiler.

3. A diffusion pump comprising a plurality of pumping jets, a condensing surface for said jets, a common boiler, a mixture of vaporizable liquids in said boiler, means below the normal surface of said liquid to provide al plurality of liquid-retaining cells, a chimney for each of said jets, one of said chimneys extending in proximity to and terminating above the normal surface of said liquids and supporting a plurality of depending baffles adapted to impede migration,

of pumping vapors between said chimneys and means for returning the condensate to a predetermined portion of said liquid-retaining cells and openings for restricting liquid iiow from said receiving cells to the remaining cells.

4. A diffusion pump comprising a pump chamber, a plurality of serially operating pumping Jets in said chamber, a common boiler for all of said jets, vapor chimneys for each of said jets, a condensing surface for condensing the vapor passing through said jets, means for returning the condensate to a predetermined portion of said boiler, one of said chimneys extending in proximity to the surface of a liquid in said boiler, baffle means for restricting vapor flow between said chimneys, and baille means submerged in the liquid in said boiler for controlling the quality of the vapor evolved under the several chimneys.

5. A diffusion pump comprising a pump chamber, a plurality of serially operating pumping jets in said chamber, a common boiler for all of said jets, vapor chimneys for each of said jets. a condensing surface for condensing the vapor passing through said jets, means for returning the condensate to a predetermined portion of said boiler, one of said chimneys extending in proximity to and terminating above the surface of a liquid in said boiler, baille means depending from one of said chimneys for restricting vapor flow between said chimneys, and baille means submerged in the liquid in said boiler for controlling the quality of the vapor evolved under the several chimneys, said last-mentioned baille means dividing said boiler into a plurality of cells.

6. A multi-stage diiusion pump of the selffractionating type comprising a common boiler for all stages of the pump, means for controlling the flow of the vapor-evolving liquid in said boiler, separate chimneys for each stage of said pump, one of said chimneys extending into closely spaced relation to and terminating above the surface of the liquid in said boiler and baille means depending from one of said chimneys for impeding the flow of vapor from one chimney to another.

'7. A self-fractionating oil-diffusion pump comprisingv a low-pressure `iet, a high-pressure jet, a common boiler for both said jets, a quantity of oil in saidboiler, a condenser cooperating with both said jets, means for returning condensate from said condenser to the outer portion of the boiler, means for impeding the flow of oil from the outerA portion of the boiler to an inner portion for vaporizing the more volatile portions of the oil near the outer portion of the boiler, baule means in the space above the surface of the oil in the boiler for impeding intermingling of the vapors generated in the outer and inner portions of the boiler, a vapor passage for conducting the vapors from the outer portion of the boiler to the high-pressure jet and a passage for conducting the vapors generated in the inner portion of the boiler to the low-pressure jet.

GLENN R. STOLTENBERG. AUGUST P. COLAIACO.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 2,153,189 Hickman Apr. 4, 1939 2,211,329 Hickman Aug. 13, 1940 2,291,054 Nelson July 28, 1942 

